Work carrier accumulation mechanism

ABSTRACT

A processing machine including rails on which a plurality of work carriers are movably mounted and are advanced therealong by means of a pusher mechanism engageable with an abutment on each work carrier. The work carriers are provided with a linkage mechanism for coacting with adjacent work carriers and cams disposed along the path of travel of the work carriers for moving the abutment out of engagement with the pusher mechanism whereby certain work carriers are temporarily retained in a stationary condition along selected locations of the processing machine as may be desired or required from time to time.

I United States Patent [1 1 3,674,127

Juve July 4, 1972 [54] WORK CARRIER ACCUMULATION MECHANISM Primary ExaminerRichard E. Aegerter At! H D' k & P' [72] Inventor: Robert J. Juve, Sterling Heights, Mlch. omey amass ey lerce [73] Assignee: The Udylite Corporation [57] ABSTRACT [22] Filed: Jan. 11, 1971 A processing machine including rails on which a plurality of work carriers are movably mounted and are advanced [21] Appl' 105531 therealong by means of a pusher mechanism engageable with an abutment on each work carrier. The work carriers are pro- UuS- vided a linkage mechanism for coacting adja ent 1 f Cl work carriers and cams disposed along the path of travel of the [58] Field ofSearch ..l98/l9,38; 104/162 work carriers for moving the abutment out of engagement with the pusher mechanism whereby certain work carriers are [56] References and temporarily retained in a stationary condition along selected UNITED STATES PATENTS locations of the processing machine as may be desired or required from time to time. 3,027,850 4/1962 Burrows ..104/l62 3,220,534 1 1/1965 Abbey ..l98/l9 9 Claims, 7 Drawing Figures BACKGROUND OF THE INVENTION The present invention is particularly applicable, but not necessarily restricted, to automatic conveying machines of the general type as described in U.S. Pat. Nos. 2,854,159; 2,979,181; 4 2,975,882; 2,987,201; 3,207,337; 3,143,975; 3,199,843; and 3,220,534. The foregoing U.S. patents describe in combination a processing machine incorporating a plurality of individual work carriers, each of which can be automatically and selectively dispatched and routed such that the workpieces carried thereon undergo a desired processing sequence which can vary from the processing sequence of workpieces on other work carriers. Processing machines of the type described in these patents are particularly adaptable for automatically transferring workpieces through a preselected chemical and electroplating processing cycle, whereby controlled variations can be made in the duration of treatment of certain workpieces at one or more treating statrons.

In view of the different treatment times of the workpieces carried on successive work carriers in accordance with the preselected processing program prescribed for each individual work carrier, it is necessary to provide one or more sections along the path of travel of the work carriers for accumulating the work carriers and from which they can be dispatched at regular timed intervals in spite of their erratic arrival at such accumulation centers. The present invention provides for an improved system for attaining an ordered accumulation of work carriers at one or more locations along their processing path which is of simple and economical construction, of durable and reliable operation and of simple and versatile control.

SUMMARY OF THE INVENTION The foregoing and other benefits and advantages of the present invention are achieved by a conveying machine of the general type as described in the aforementioned U.S. patents which includes a rail or track extending along a suitable processing path on which a plurality of work carriers are movably mounted and are advanced therealong by a transfer mechanism adapted to coact with an abutment on each work carrier. The abutment on each work carrier is movable to and from an operative position in which it is engageable by the transfer mechanism and an inoperative position in which it is disposed in clearance relationship relative to the transfer mechanism, whereupon the work carrier remains in a stationary condition until such time that the abutment again is moved to the operative position. Linkage means are provided on each work carrier which are operatively associated with the abutment and are effective for causing movement thereof between the operative and inoperative position. In addition, suitable actuating means are provided on the frame of each work carrier, which is disposed so as to coact with the linkage means on an adjacent work carrier for effecting movement of the abutment of such adjacent carrier to an inoperative position in response to the approaching movement of the adjacent carrier to within a preselected distance of the actuating carrier, whereupon an accumulation of work carriers can occur. Each work carrier is provided with means for selectively positioning the actuating means thereon in an engaging or non-engaging position consistent with the particular direction of travel of the work carriers in order to avoid any interference and/or binding of the linkage means thereon.

In addition to the foregoing arrangement, suitable selectively actuatable cams are provided at one or more locations along the processing path which are adapted to coact with and move the abutment to an inoperative position, initiating a work carrier accumulation condition at that particular location.

Still further advantages and benefits of the present invention will become apparent upon a reading of the description of the preferred embodiments, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a typical process layout through which workpieces supported by a plurality of movable work carriers are adapted to be advanced and undergo a prescribed treating sequence;

FIG. 2 is a fragmentary perspective view of a portion of the automatic conveying machine including one work carrier in a lowered position and a second work carrier in a raised position on the supporting tracks;

FIG. 3 is a fragmentary plan view of a work carrier supported on the guide tracks;

FIG. 4 is a fragmentary side elevation view, partly in section, of portions of the work carrier and track arrangement shown in FIG. 3;

FIG. 5 is a fragmentary side elevational view of an actuating cam mechanism mounted on the track as shown in FIG. 4;

FIG. 6 is a fragmentary plan view showing the cam and slide arrangement for selectively positioning the actuators on a work carrier in an engaging and non-engaging position; and

FIG. 7 is a fragmentary side elevational view of the work carrier shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the drawings and as may be best seen in FIG. 1, a typical processing arrangement is illustrated for applying a tin plating over a copper strike on metallic workpieces, which is preceded by an appropriate pretreatment including various cleaning and rinsing steps. The work carriers incorporating workpieces thereon move in a counterclockwise direction, as indicated by the arrows in FIG. 1, commencing at a load and unload station indicated at L. Each work carrier, after having been loaded and programmed for a selected processing sequence, is individually transferred by a cross shuttle 10 to a front section 12 of the processing machine along which the workpieces undergo an appropriate pretreatment cycle, including, for example, cleaning, pickling and intervening rinses in stations S1 through S17, inclusive. The work carriers thereafter are transferred to the output end of the machine section 12, at which they are accumulated, if necessary, along the section indicated at Al prior to being transferred by cross shuttle 14 to the rear section 16 of the processing machine. The work carries and the workpieces undergo an appropriate electroplating treatment at stations SIS-S28, whereafter they are transferred to an accumulation section indicated at A2 at the output end of the machine section 16. The workpieces are appropriately unloaded and reloaded at the load station, L whereafter they again are transferred by means of the cross shuttle 10 to the input end of machine section 12.

It will be evident from the foregoing arrangement that selected variations in the dispatching and total treatment periods of the workpieces on selected work carriers causes variations in the time required for different work carriers to complete the pretreatment and electroplating cycles, necessitating a careful coordination of the transfer movement of the work carriers to avoid interference. Such erratic movement of the work carriers is overcome by providing one or more work carrier accumulation centers or locations at which the work carriers are accumulated to permit a rerouting thereof at appropriate timed intervals and in coordinated timing with other machine operations. In this regard, the operation of the cross shuttle 10 and 14 is conventionally performed on a prescribed time cycle and it is, accordingly, necessary that the work carriers be transferred to the input ends of the shuttles 10, 14 at timed intervals not less than the time period required for such shuttle conveyors to complete a round trip. For this purpose, accumulation section Al and accumulation section A2 are provided at which, in spite of the erratic time intervals at which work carriers arrive, they can be dispatched from the output end of the accumulation section at any desired time interval in order to provide satisfactory operation.

The essential structural features of an automatic conveying machine and movable work carriers to which the present invention is applicable is best seen in FIGS. 2-4 of the drawings. The conveying machine, as shown, corresponds to the automatic processing machine as described in the aforementioned U.S. patents, the subject matter of which is incorporated herein by reference and to which reference is made for further details concerning the structural and operating features of conveying machines of such type.

The processing machine comprises, as shown in FIGS. 2-4, a framework having a pair of opposed channel tracks or rails 18, within which rollers on work carriers 22 are rotatably disposed. The track 18 is comprised of a plurality of individual sections or segments including fixed segments and vertically movable segments which are adapted to be disposed in end-toend alignment forming a continuous elevated track. Each of the vertically movable track segments is mounted on an elevator frame 24 at each station to effect a lowering of the work carrier and the workpieces supported thereon into a treating solution as may be contained in treating receptacles 26. When the elevator frame 24 is lowered, a suitable replacement track section is interposed in the gap formed between the elevated fixed track sections so as to maintain continuity of the transfer track, enabling other work carriers to be transferred above those work carriers which are in the lowered or treating position. Movement of the elevator frame and work carrier thereon is suitably achieved such as by means of a double-acting fluid-actuated cylinder 28. Guided movement of the elevator frame to and from the raised and lowered position is achieved such as by means of vertical guide members affixed to the machine framework.

Each work carrier 22 comprises a framework including a cantilever work supporting arm 32 from which the workpieces are suspended either directly or by means such as a rack 34 or barrel 36 on the arms of the work carriers shown in FIG. 2. A transverse angle member 38, as shown in FIGS. 3 and 4, is affixed to the upper surface of each work supporting arm 32, on which one pair of the work carrier rollers 20' are rotatably supported by means of stub axles 40. A second or forward pair of rollers 20 similarly are mounted on stub axles 40 affixed to a cross plate 42 having its lower edge welded or otherwise securely fastened to a base plate 44 affixed to the upper side of the work supporting arm 32. In the specific embodiment illustrated, the base plate 44 and angle member 38 are affixed by means of bolts 46 to the upper flange defining the work supporting arm. In addition to the supporting rollers 20, a pair of guide rollers 48, as best seen in FIGS. 4 and 7, is provided, each of which is rotatably affixed to the inner edge of the base plate 44 and is disposed in rolling engagement with an inverted channel guide track 50 affixed to the lower inner surface of the outer guide track 18.

Advancement of the work carriers along the guide track 18 is achieved by a suitable transfer mechanism, such as a transfer or pusher bar 52, slidably supported on the machine framework above the guide track 18, as shown in FIG. 2, and incorporating a plurality of transfer pawls or pushers 54 mounted at longitudinally spaced intervals therealong. The transfer or pusher pawls 54 are adapted to engage the upper end of an abutment 56, as best seen in FIG. 7, which is slidably mounted for vertical reciprocation within a rectangular tubular sleeve 58 affixed to and projecting upwardly of the upper surface of the base plate 44. The abutment 56 is provided with a laterally extending pin or cam follower 60 and the upper edge of the sleeve 58, as shown in FIG. 7, is notched, as at 62, to accommodate the pin 60 when the abutment is moved downwardly such that the upper end thereof is disposed below and in clearance relationship relative to the pusher 54.

The sleeve 58 is further formed with a pair of vertically extending slots 64, as best seen in FIGS. 4 and 6, through which the end portions of arms 66a, 66b extend and are disposed in engagement with recesses 68 formed in the abutment 56. Each arm 66a, 66b is pivotally secured by means of a shaft 70a, 70b, which is affixed to and projects laterally of the cross plate 42. As will be noted in FIG. 6, shaft 70a, 70b are of different lengths whereby arms 66a and 6b are laterally offset relative to the longitudinal axis of travel of the work carrier. Each arm 66a, 66b is formed with an angularly offset shoe 72a, 72b at the end thereof for purposes subsequently to be described.

The coaction between the end portions of the arms 66a, 66b with the slot 64 in the sleeve and the recesses 68 in the abutment serves to restrain movement of the abutment outwardly of the sleeve beyond the position as shown in solid lines in FIGS. 4 and 7. The abutment is normally biased toward a raised or operative position in which it is engageable by the pusher 54 by means of a resilient member, such as a coil spring 74, having one end seated against the base plate and the other end portion disposed within a circular recess 76 formed in the base of the abutment as shown in FIG. 7.

During normal operation, the abutment 56 is in a raised or operative position such that the pushers on the transfer mechanism are effective to cause advancement of the work carrier along the processing path consistent with the programmed processing cycle. When the work carrier is ad-' vanced into a section at which an accumulation of work carriers is to be accomplished, the abutment is moved downwardly to an inoperative position in which the pushers on the transfer mechanism are disposed in clearance relationship whereby the work carrier remains stationary until such time that the abutment is again raised. In accordance with the arrangement comprising the present invention, the abutment is moved to the inoperative position in opposition to the biasing force of the coil spring 74 by means either of a cam actuator 78 operative to engage and depress the pin 60 on the abutment or by means of an upward pivoting movement of either of the linkage arms 66a, 66b in response to coaction with actuators 80a, 80b on an adjacent work carrier responsive to movement of the work carrier within a preset distance from a preceding work carrier. The cam actuator is employed for disabling the first work carrier at an accumulation section to initiate an accumulation of work carriers and is also operative to release and render the abutment operative to effect a transfer of that work carrier downstream from the accumulation section. The pivoted link arms and actuators on the work carriers, on the other hand, are operative to stop successive work carriers after an accumulation has begun and to avoid a clashing of work carriers during their transfer movement into the input end of an accumulation section.

The cam actuator mechanism will now be described with particular reference to FIGS. 1, 4 and 5 of the drawings. The cam actuator 78 is mounted for lateral reciprocating movement to and from a retracted or inoperative position, as shown in solid lines in FIG. 4, to a projected or operative position as shown in phantom in which it is disposed in the path of the pin 60 projecting laterally of the abutment 56. The cam actuator is affixed to the end of a slide block 82 which is slidably disposed within a guide shoe 84 affixed to the upper surface of a cross member 86 extending between the tracks 18. The slide block 82 is secured to the rod end 88 of a double-acting fluidactuated cylinder 100. The actuation of the cylinder to effect a movement of the cam actuator to the operative position may be conveniently achieved, for example, in response to the tripping of a suitable sensing device, such as a limit switch LS1 (FIGS. 1 and 4) located adjacent to the path of travel of the work carrier. The limit switch may conveniently be located near the output end of an accumulation section, such as the section A1, effecting a stopping of the work carrier prior to entry on the cross shuttle 14.

The tripping of limit switch LS1 is operable in accordance with any circuitry well known in the art to effect the opening of a suitable remotely actuatable valve causing pressurized fluid to flow into the blank end of the cylinder 100 such that the cam actuator 78 is moved to the projected or operative position. As the work carrier approaches the cam actuator while in an operative position, the laterally projecting pin 60, as shown in FIG. 5, engages the cam surface 102 on the cam actuator causing a progressive downward movement of the abutment in response to further advancing movement of the work carrier. The position of the pin 60 upon entryinto the cam is shown in phantom in FIG. 5, whereas the position with the pin and abutment in the fully lowered position is indicated in solid lines. Upon attainment of the fully lowered position, the pusher on the transfer mechanism becomes disengaged from the abutment, whereby the work carrier comes to a halt in that location and remains in that position until the pin 60 is released.

An actuation of the hydraulic cylinder to effect a retraction of the cam actuator, thereby releasing the abutment, can be achieved automatically in response to a prescribed time sequence such as by a suitable dwell timer of the types known in the art incorporated in the control circuit of the machine. Alternatively, retraction of the cam actuator can be performed in accordance with the arrangement as shown in FIG. 1 in response to the arrival of the shuttle carriage of the cross shuttle 14 in a position to receive a work carrier positioned at the output end of the accumulation section Al. Upon a retraction of the cam actuator, the biasing force of the coil spring 74 (FIG. 7) causes the abutment to again move toward the raised or operative position whereupon the pusher 54 engages and effects a transfer movement of the work carrier.

Movement of the abutment 56 to the inoperative position is also accomplished in response to the approaching movement of a work carrier toward a stationary work carrier on the guide track. This occurs in response to the coaction of a shoe 72a or 72b with a corresponding actuator 80a or 80b on the adjacent work carrier, effecting a pivoting movement of the linkage arms such as from the position as shown in solid lines in FIG. 7 to a raised position, shown in phantom, accompanied by a downward movement of the abutment 56 to the inoperative position. The particular arm and actuator which effect a disengagement of the work carrier from the transfer mechanism is dependent on the direction of the advancing movement of the work carrier. In the specific arrangement shown in the drawing, the arm 66a extends in the direction of travel of the work carriers during their transfer along machine section 12 such that they are operative to coact with actuators 80b on work carriers stationarily disposed on the guide track. Conversely, arm 66b is operative to coact with actuator 80 a on a work carrier that is overtaken during the transfer of work carriers along machine section 16 or toward the left as viewed in FIG. I. In order to avoid interference between the trailing arm on a work carrier and an actuator on the overtaking work carrier, the actuators 80a, 80b are selectively positionable between engageable and non-engageable positions in accordance with the direction of transfer of the work carrier in a manner and for the purposes as hereinafter described.

As best seen in FIGS. 6 and 7, the actuator 80a is mounted on a slide plate 104a and the actuator 80b similarly is mounted on a slide plate 104b, which are mounted for transverse reciprocating movement on the underside of the leading and trailing edges of the base plate 44. The side edges of each slide plate are disposed in guided coaction with spacer strips 106 while retainer strips 108 overlie the lower surfaces thereof along the length of their edges.

Each actuator 80a, 80b is comprised of an inverted L- shaped member comprising an upstanding bracket 110 connected to a laterally and substantially horizontally disposed actuator plate 112 including a reinforcing fillet 114. The leading edge of the actuator plate 112 is adapted to coact with the shoe such as the shoe 72a of arm 66a effecting pivoting movement thereof in a manner as shown in FIG. &.

As is best seen in FIG. 6, the inner terminal edge of each slide plate 141:, l04b is formed with a cam block 116 which is adapted to engage cams H8, 120 in response to the movement of the work carrier, effecting an appropriate reciprocating movement thereof and a corresponding positioning of the actuator 80a, 80b thereon either in an engageable or non-engageable position as the case may be. In the specific arrangement as shown in FIGS. 6 and 7, the work carrier is traveling in a direction toward the left such that the arm 66a thereon is in a leading position, while the arm 66b is in a trailing position. As previously indicated, it is the leading arm which effects a retraction of the abutment to the inoperative position and this is accomplished by means of its coaction with an actuator b on the work carrier being overtaken. Accordingly, all work carriers moving in the direction of the work carrier shown in FIGS. 6 and 7 corresponding to the direction of travel along machine section 12 are cam actuated by means of the cam 118 such that the slide plates 104a, 104k thereon are in the position as shown in solid lines and wherein the actuator 80a is in the non-engaging position and the actuator 80b is in the engaging position. The movement of the slide plates 104a, 1041; to the position as shown in FIG. 6 is achieved by the coaction of cam block 116 with the cam surface of cam 118 in response to the movement of the work carrier toward the left, as viewed in FIG. 6. When in the engaging position, the actuators are disposed in longitudinal coacting alignment with the shoe on the leading arm of the adjacent carrier. On the other hand, when the actuators are in the non-engaging position, they are disposed in lateral clearance relationship relative to'the trailing arm of the work carrier being overtaken such that the trailing arm is in a slave position and its movement is controlled by the movement of the abutment in response to either actuation of the pin 60 thereon or pivoting movement of the leading arm.

In order to accommodate the actuators 80a, 80b, permitting lateral reciprocating movement thereof in response to movement of the slide plates 1040, 104b, respectively, and to further provide clearance when the actuators are disposed in the non-engaging position, the base plate 144 is formed with a notch indicated at 122. In accordance with the foregoing operation, the slide plates 104a, [04b and the actuators thereon are adapted to be moved from the position as shown in solid lines in FIG. 6 to the position shown in phantom such as by coaction with the cam surface of cam 120, whereupon actuator 80b is disposed in the non-engaging position, while actuator 80a is in the engaging position. The foregoing disposition of the actuators is appropriate for a travel of the work carriers in a direction toward the right, as viewed in FIG. 6, in which the leading arm 66b is rendered operative for retracting the abutment in response to coacting with an actuator 80a on a work carrier being overtaken. The appropriate positioning of the slide plates and the actuators thereon is achieved by an appropriate positioning of the cams 118, 120, either at the input of the machine section or, alternatively, at the output end thereof as they are advanced onto the cross shuttle upon movement outwardly of the accumulation section.

While it will be apparent that the invention herein disclosed is well calculated to achieve the benefits and advantages as hereinabove set forth, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the spirit thereof.

What is claimed is:

l. A work carrier comprising a frame including work supporting means thereon, means on said frame for movably mounting said work carrier on guide means for guided travel along a processing path, an abutment on said frame movable to and from an operative position in which it is engageable by a transfer device and an inoperative position disposed in clearance relationship relative to the transfer device, linkage means operatively associated with said abutment for effecting movement thereof between said operative position and said inoperative position, actuating means on said frame for coacting with linkage means on an adjacent said work carrier for moving said abutment on the adjacent said carrier to said inoperative position in response to the approaching movement of the adjacent said carrier to within a preselected distance, said actuating means comprising a pair of actuators on said frame selectively and alternatively positionable between an engaging position and a non-engaging position relative to the linkage means on an adjacent said work carrier such that when one actuator is in said engaging position the other actuator is in said non-engaging position.

2. A work carrier as defined in claim 1, further including biasing means for urging said abutment toward said operative position.

3. The work carrier as defined in claim 1, wherein said linkage means comprises a pair of actuatable arms on said frame extending toward the leading and the trailing sides of said work carrier.

4. The work carrier as defined in claim 1, in which said actuating means are mounted for movement transversely relative to the direction of travel of said work carrier and are positionable in said engaging and said non-engaging position in response to coaction with cam means located along said processing path.

5. The work carrier as defined in claim 1, further including a cam follower on said abutment and operable for effecting movement of said abutment to said inoperative position independently of said linkage means in response to the coacting camming movement of cam actuator means disposed along said processing path during the course of the advancing movement of said work carrier.

6. The work carrier as defined in claim 1, wherein said abutment is mounted for reciprocating movement in a guide sleeve to and from said operative and said inoperative position.

7. The work carrier as defined in claim 1, wherein said linkage means comprises a pair of actuatable arms pivotally mounted on said frame, said arms extending in opposite directions in a leading and trailing position, respectively, relative to the path of travel of said work carrier and with the outer projecting ends thereof disposed in lateral offset relationship, the inner end portions of said arm operatively connected to said abutment for effecting reciprocating movement thereof in response to pivoting movement of said arms.

8. A processing machine comprising a framework, guide means on said framework, a plurality of work carriers movably mounted on said guide means, transfer means for effecting advancement of said work carriers along said guide means, each said work carrier including a frame and an abutment on said frame movable to and from an operative position in which it is engageable by said transfer means and an inoperative position disposed in non-engageable relationship relative to said transfer means, linkage means on said frame operatively associated with said abutment for effecting movement thereof between said operative and said inoperative position, actuating means on each said frame for coacting with said linkage means on an adjacent said work carrier for moving said abutment of the adjacent said work carrier to said inoperative position in response to the approaching movement of the adjacent said work carrier to within a preselected distance, said actuating means on each said frame selectively positionable between an engaging position and a non-engaging position relative to the linkage means on an adjacent said work carrier, said machine further including a cam follower on said abutment of each said work carrier and cam actuator means on said framework movable to and from an aligned position in which it is operative to coact with said cam follower for moving said abutment to said inoperative position and a non-aligned position in non-coacting relationship relative to said cam follower.

9. The processing machine as defined in claim 8, in which said actuating means on each said work carrier are mounted for transverse movement relative to the direction of travel of said work carriers, and cam means on said framework adjacent said guide means for coacting and positioning said actuator means in response to relative movement therebetween. 

1. A work carrier comprising a frame including work supporting means thereon, means on said frame for movably mounting said work carrier on guide means for guided travel along a processing path, an abutment on said frame movable to and from an operative position in which it is engageable by a transfer device and an inoperative position disposed in clearance relationship relative to the transfer device, linkage means operatively associated with said abutment for effecting movement thereof between said operative position and said inoperative position, actuating means on said frame for coacting with linkage means on an adjacent said work carrier for moving said abutment on the adjacent said carrier to said inoperative position in response to the approaching movement of the adjacent said carrier to within a preselected distance, said actuating means comprising a pair of actuators on said frame selectively and alternatively positionable between an engaging position and a non-engaging position relative to the linkage means on an adjacent said work carrier such that when one actuator is in said engaging position the other actuator is in said non-engaging position.
 2. A work carrier as defined in claim 1, further including biasing means for urging said abutment toward said operative position.
 3. The work carrier as defined in claim 1, wherein said linkage means comprises a pair of actuatable arms on said frame extending toward the leading and the trailing sides of said work carrier.
 4. The work carrier as defined in claim 1, in which said actuating means are mounted for movement transversely relative to the direction of travel of said work carrier and are positionable in said engaging and said non-engaging position in response to coaction with cam means located along said processing path.
 5. The work carrier as defined in claim 1, further including a cam follower on said abutment and operable for effecting movement of said abutment to said inoperative position independently of said linkage means in response to the coacting camming movement of cam actuator means disposed along said processing path during the course of the advancing movement of said work carrier.
 6. The work carrier as defined in claim 1, wherein said abutment is mounted for reciprocating movement in a guide sleeve to and from said operative and said inoperative position.
 7. The work carrier as defined in claim 1, wherein said linkage means comprises a pair of actuatable arms pivOtally mounted on said frame, said arms extending in opposite directions in a leading and trailing position, respectively, relative to the path of travel of said work carrier and with the outer projecting ends thereof disposed in lateral offset relationship, the inner end portions of said arm operatively connected to said abutment for effecting reciprocating movement thereof in response to pivoting movement of said arms.
 8. A processing machine comprising a framework, guide means on said framework, a plurality of work carriers movably mounted on said guide means, transfer means for effecting advancement of said work carriers along said guide means, each said work carrier including a frame and an abutment on said frame movable to and from an operative position in which it is engageable by said transfer means and an inoperative position disposed in non-engageable relationship relative to said transfer means, linkage means on said frame operatively associated with said abutment for effecting movement thereof between said operative and said inoperative position, actuating means on each said frame for coacting with said linkage means on an adjacent said work carrier for moving said abutment of the adjacent said work carrier to said inoperative position in response to the approaching movement of the adjacent said work carrier to within a preselected distance, said actuating means on each said frame selectively positionable between an engaging position and a non-engaging position relative to the linkage means on an adjacent said work carrier, said machine further including a cam follower on said abutment of each said work carrier and cam actuator means on said framework movable to and from an aligned position in which it is operative to coact with said cam follower for moving said abutment to said inoperative position and a non-aligned position in non-coacting relationship relative to said cam follower.
 9. The processing machine as defined in claim 8, in which said actuating means on each said work carrier are mounted for transverse movement relative to the direction of travel of said work carriers, and cam means on said framework adjacent said guide means for coacting and positioning said actuator means in response to relative movement therebetween. 